Prediction system and chemical solution

Abstract

To provide a prediction system and a chemical solution that can predict the occurrence of defects in paper and thereby prevent the occurrence of defects in paper. [Solution] The present invention provides a prediction system and chemical solution comprising a measurement unit 30 for measuring the water quality of a pulp suspension, an imaging unit 40 for imaging paper that has passed through a dry part, and a control unit 20 connected to the measurement unit and the imaging unit, wherein the water quality measurement is at least one selected from the group consisting of suspended solids measurement, turbidity measurement, ash measurement, oxidation-reduction potential measurement, raw material total concentration measurement, raw material yield measurement, ash yield measurement, conductivity measurement, water temperature measurement, and pH measurement, and the control unit 20 has an acquisition means 21 for acquiring image data and measurement results, a detection means 22 for detecting precursory defects, an extraction means 23 for extracting features of precursory defects, a classification means 24 for classifying precursory defects by type, a model acquisition means 25 for acquiring a prediction model showing the relationship between measurement information and defect count information, a setting means 26 for setting a threshold for the calculated measurement results obtained from the prediction model, and a transmission means 27 for transmitting an alert when the actual measurement results exceed the threshold.

Description

[Technical Field]

[0001] The present invention relates to a prediction system and chemical solution for predicting the occurrence of defects in paper when paper is produced by papermaking a pulp suspension. [Background technology]

[0002] The manufacture of paper involves a raw material process in which a dried pulp sheet is defibrated, a preparation process in which additives such as fillers and sizing agents are added to this and stirred and mixed to form a pulp suspension, a wet part in which this pulp suspension is separated using a papermaking machine to remove the water contained in the pulp suspension and form wet paper, or a wet part in which the water contained in the pulp suspension is removed and compressed with a press roll to form wet paper, a dry part in which the wet paper is dried to form paper, and a reel part in which the paper is wound up.

[0003] In the papermaking process, from the viewpoint of productivity, paper (including the "wet paper") is transported at an extremely high speed. Therefore, if problems such as paper breaks (i.e., the paper is cut) or pitch contamination (i.e., pitch adheres to the paper) occur, the yield will drop significantly. Therefore, various techniques have been developed in the papermaking process to minimize the occurrence of problems such as paper breaks and pitch contamination.

[0004] For example, a monitoring system is known that includes a papermaking machine for manufacturing paper, an application device for applying a chemical solution to parts of the papermaking machine that come into direct or indirect contact with the paper while the papermaking machine is operating, a control panel for setting the application conditions of the application device, a surveillance camera for monitoring the parts to be monitored, and a control device connected to the surveillance camera via a network (see, for example, Patent Document 1). This monitoring system targets the dry part and monitors using images captured by a monitoring camera.

[0005] Also, a defect classification system is known for classifying defect information based on defects in paper that has undergone the dry part in the papermaking process after the stock preparation process into a corresponding defect cause item from among a plurality of defect cause items based on preset defect causes, the defect classification system comprising: an imaging means for imaging the paper that has undergone the dry part using an imaging device and acquiring the image data of the image; a detection means for detecting paper defects in the image data; an extraction means for extracting feature quantities of the defects; a calculation means for calculating the certainty of the defect cause item based on the defect feature quantities using a classification model for which reference feature quantities have been set in advance, and calculating the certainty for each defect cause item; a display means for displaying the certainty; and a classification means for classifying the defect information into the defect cause item with the highest certainty among the plurality of certainty quantities (see, for example, Patent Document 2). Such a defect classification system extracts defects in paper from captured image data and classifies them into predetermined defect cause items. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6697132 [Patent Document 2] Patent No. 7390085 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the monitoring system described in Patent Document 1, the object of monitoring is limited to the dry part, and it cannot be said to be sufficient from the viewpoint of predicting the occurrence of problems with paper. In the defect classification system described in Patent Document 2, although it is possible to take measures by classifying defects, it cannot be said to be sufficient from the viewpoint of predicting the occurrence of problems with paper.

[0008] The present invention has been made in consideration of the above circumstances, and aims to provide a prediction system and chemical solution that can predict the occurrence of defects in paper, thereby preventing the occurrence of defects in paper. [Means for solving the problem]

[0009] The present inventors conducted extensive research to solve the above problems and came to the conclusion that there may be a correlation between measurement information from water quality measurements of pulp suspensions and defect number information related to predictive defects. The inventors then discovered that the above problem can be solved by creating a prediction model from this information and setting a threshold value for the calculation and measurement results obtained from the prediction model, which led to the completion of the present invention.

[0010] The present invention provides a prediction system for predicting the occurrence of defects in paper when paper is manufactured by making a pulp suspension using a papermaking machine having at least a wet part and a dry part, the prediction system comprising a measurement unit for measuring the water quality of the pulp suspension, an imaging unit for imaging the paper after it has passed through the dry part, and a control unit connected to the measurement unit and the imaging unit via a network, wherein the water quality measurement is at least one selected from the group consisting of suspended solids measurement, turbidity measurement, ash content measurement, oxidation-reduction potential measurement, raw material total concentration measurement, raw material yield measurement, ash content measurement, conductivity measurement, water temperature measurement, and pH measurement, and the control unit measures the water quality by capturing the image data from the imaging unit. a detection means for detecting at least a precursor defect that is a sign of a malfunction in the image data; an extraction means for extracting feature quantities of the precursor defect; a classification means for classifying the precursor defect by type from the feature quantities; a model acquisition means for acquiring a prediction model that shows the relationship between measurement information, which is time-series data of the water quality measurement results, and defect number information, which is time-series data of precursor defects for each type; a setting means for setting a threshold value for the calculated measurement results obtained from the prediction model; and a transmission means for transmitting an alert when the actual measurement results exceed the threshold value.

[0011] It is also preferable that the control unit further comprises an addition command means for issuing a command to add or increase the amount of chemical solution to the pulp suspension when the actual measurement result exceeds a threshold value. It is more preferable that the chemical solution contains at least one selected from the group consisting of a pitch control agent, a slime control agent, a paper strength agent, a sizing agent, a retention aid, a coagulant, and aluminum sulfate.

[0012] In the prediction system of the present invention, it is preferable that the defect is a defect caused by pitch contamination, the water quality measurement is at least one selected from the group consisting of suspended solids measurement, turbidity measurement, ash measurement, raw material yield measurement, ash yield measurement, and conductivity measurement, and the predictive defect is a micro-pitch defect caused by micro-pitch. In this case, it is preferable that the control unit further includes an addition command means for issuing a command to add or increase the amount of a chemical solution containing at least one selected from the group consisting of a pitch control agent, a paper strength agent, a retention aid, a coagulant, and aluminum sulfate to the pulp suspension when the actual measurement result exceeds a threshold value.

[0013] In the prediction system of the present invention, it is preferable that the defect is a defect caused by paper breakage, the water quality measurement is at least one selected from the group consisting of oxidation-reduction potential measurement, water temperature measurement, and pH measurement, and the precursor defect is a peeling defect caused by peeling, a weaving defect caused by weaving, or an edge split defect caused by edge splitting. In this case, it is preferable that the control unit further has an addition command means that issues a command to add or increase the amount of a chemical solution containing a slime control agent to the pulp suspension when the actual measurement result exceeds a threshold value.

[0014] The present invention relates to a chemical solution that is added or increased to a pulp suspension when the actual measurement result exceeds a threshold value in the above-mentioned prediction system, and that includes at least one selected from the group consisting of a pitch control agent, a slime control agent, a paper strength agent, a sizing agent, a retention agent, a coagulant, and aluminum sulfate. [Effects of the Invention]

[0015] In the prediction system of the present invention, the acquisition means, detection means, extraction means, and classification means of the control unit can detect predictive defects in image data and classify the predictive defects by type. Incidentally, even predictive defects have different increasing trends until the occurrence of defects depending on the type, so classification is extremely important. Furthermore, in the prediction system, the model acquisition means of the control unit acquires a prediction model, the setting means sets a threshold for the calculated measurement results obtained from the prediction model, and the transmission means transmits an alert when the actual measurement results exceed the threshold, so that by measuring water quality over time, it is possible to recognize an increase in the number of specific precursor defects. In other words, an increase in the number of specific precursor defects makes it possible to predict the possibility that they will become paper defects in the future.

[0016] In the prediction system of the present invention, the chemical solution can be added or increased to the pulp suspension by a command from the addition command means of the control unit. This improves the results of water quality measurements and prevents problems from occurring on the paper. In this case, if the chemical solution contains at least one selected from the group consisting of pitch control agents, slime control agents, paper strength agents, sizing agents, retention agents, coagulants, and aluminum sulfate, the occurrence of defects in the paper can be sufficiently prevented.

[0017] In the prediction system of the present invention, for example, when it is desired to predict defects due to pitch contamination, a prediction model can be obtained and used from measurement information obtained by performing at least one water quality measurement selected from the group consisting of suspended solids measurement, turbidity measurement, ash measurement, raw material yield measurement, ash yield measurement, and conductivity measurement, and defect number information for micro-pitch defects. This makes it possible to predict in the future whether or not a problem due to pitch contamination of paper may occur by actually measuring the corresponding water quality. At this time, by issuing a command from the addition command means to add or increase the amount of a chemical solution containing at least one selected from the group consisting of a pitch control agent, a paper strength agent, a retention aid, a coagulant, and aluminum sulfate to the pulp suspension, the measurement results of the corresponding water quality measurement can be improved and defects caused by pitch contamination in the paper can be prevented.

[0018] In the prediction system of the present invention, for example, if one wishes to predict defects due to paper breakage, a prediction model can be obtained from measurement information obtained by performing at least one water quality measurement selected from the group consisting of oxidation-reduction potential measurement, water temperature measurement, and pH measurement, and information on the number of defects such as peeling defects, incorporation defects, or edge cracking defects, and then used. This makes it possible to predict whether a particular problem may lead to paper breakage in the future by actually measuring the corresponding water quality. At this time, by issuing a command from the addition command means, a chemical solution containing a slime control agent can be added or increased to the pulp suspension, thereby improving the measurement results of the corresponding water quality measurement and preventing defects such as paper breaks from occurring.

[0019] The chemical solution of the present invention contains at least one selected from the group consisting of pitch control agents, slime control agents, paper strength agents, sizing agents, retention agents, coagulants, and aluminum sulfate, thereby improving the results of water quality measurements and preventing problems from occurring in the paper. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a schematic diagram for explaining a paper machine in which a prediction system according to this embodiment is used. [Figure 2] FIG. 2 is a schematic diagram for explaining the measurement unit in the prediction system according to this embodiment. [Figure 3] FIG. 3 is a schematic diagram for explaining an example of an installation position where the measurement unit of the prediction system according to this embodiment is installed. [Figure 4]FIG. 4 is a block diagram showing a control unit in the prediction system according to this embodiment. [Figure 5] FIG. 5 is a graph showing the relationship between measurement information, which is data over time on the measurement results of the amount of suspended solids, and defect number information, which is data over time on the number of fine pitch defects, in the prediction system according to this embodiment. [Figure 6] Figure 6 is a graph showing the relationship between measurement information, which is data over time on the measurement results of the amount of suspended solids, and defect number information, which is data over time on the total number of micro-pitch defects and non-micro, normal-sized pitch defects, in the prediction system of this embodiment. [Figure 7] FIG. 7 is a graph showing the relationship between measurement information, which is data over time on the measurement results of the oxidation-reduction potential, and paper break occurrence information, which is data over time on whether or not a paper break has occurred, in the prediction system according to this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings as necessary. In the drawings, the same elements are denoted by the same reference numerals, and redundant explanations will be omitted. Furthermore, unless otherwise specified, the positional relationships such as up, down, left, and right will be based on the positional relationships shown in the drawings. Furthermore, the dimensional ratios of the drawings are not limited to those shown in the drawings.

[0022] In this specification, the term "pulp suspension" refers to a suspension of dispersed pulp (hereinafter referred to as "pulp dispersion"), which is a raw material for paper, with or without additives. The pulp suspension includes not only virgin raw materials but also white water recovered in the wet part and a mixture of the virgin raw materials and the white water. A "defect" in paper refers to a state in which poor quality occurs in the paper, such as defects due to pitch contamination or defects due to paper breaks. A "premonitory defect" is a defect that is a sign of a problem with the paper. "Pitch" is a contaminant contained in pulp, which includes sticky substances derived from adhesive tape and glue, and sticky substances derived from wood. "Fine pitch defects" are defects caused by fine pitches of less than N mm in maximum diameter. The value of N can be set arbitrarily. It is generally set to less than 10 mm or less than 8 mm. The setting may also be changed depending on the required quality of the paper. For example, it may be set to less than 2 mm for white cardboard, and less than 15 mm for corrugated board. Even if minute pitch defects are so minute that they do not cause problems in themselves, they will gradually grow and cause problems due to pitch contamination. Layer separation is a defect that occurs when foreign matter gets mixed in between layers of paper, causing poor adhesion between the layers and making them appear to have peeled off. Even if the peeling defect itself does not cause a problem, it will gradually grow and cause problems such as paper breaks. A "defect from stock preparation" is a defect in which foreign matter mixed in the pulp suspension is incorporated into the paper, causing the foreign matter to appear on the surface of the paper or holes to form around the foreign matter. Even if the incorporation defect does not itself cause a problem, it will gradually grow and cause problems such as paper breaks. Edge cracks are defects that occur when foreign matter adheres to both edges of paper or when poor formation occurs, causing the edges of the paper to split as the paper dries. Even if the edge split defect itself does not cause a problem, it will gradually grow and cause problems such as paper breaks.

[0023] FIG. 1 is a schematic diagram for explaining a paper machine in which a prediction system according to this embodiment is used. As shown in Figure 1, the papermaking machine 10 has at least a head box 1 into which the pulp suspension prepared in the preparation process is fed, a wire part 2 in which the pulp suspension is poured onto a wire and the water is removed to form wet paper, and a press part 3 in which the wet paper is pressed through a felt to remove excess water; a wet part 2a consisting of a dry part 4 in which the wet paper is heated and dried; a reel part 5 in which the dried wet paper is wound onto a spool or the like; and a white water pit 6 installed below the wire part 2.

[0024] In the paper machine 10, the pulp suspension is made into paper by passing through these parts, and paper is produced. The paper to be produced here is not particularly limited as long as it can be produced by a papermaking process, and examples that can be used include so-called western paper such as printing paper, newsprint, coated paper, packaging paper, thin paper, household paper such as toilet paper and tissue paper, miscellaneous paper, and so-called layered paperboard such as cardboard base paper, white paperboard, colored paperboard, paper tube base paper, building material base paper, and various mounts.

[0025] In the wire part 2, the water (white water) that falls is stored in a white water pit 6 installed below. In addition, in the press part 3, the water (white water) discharged from the wet paper is absorbed by the felt and collected by a felt suction box (not shown) installed on the felt. The recovered water is separated into gas and liquid in a separator, and only the white water is sent to a white water pit and stored there. The white water stored in the white water pit 6 contains a pulp dispersion, and is discharged from the white water pit 6 at an appropriate time to be disposed of as waste liquid or recycled.

[0026] The prediction system according to this embodiment is implemented using the paper machine 10 described above, and is a system for predicting the occurrence of defects in paper caused by pitch. The prediction system includes a measurement unit 30 for measuring the water quality of the pulp suspension fed from the head box 1 to the wire part 2, an imaging unit 40 for capturing images of the paper that has passed through the dry part 4, and a control unit 20 connected to the measurement unit 30 and the imaging unit 40 via a network. The network may be wired or wireless.

[0027] The measurement unit 30 has a measurement device for measuring the water quality of the pulp suspension by at least one method selected from the group consisting of suspended solids (SS), turbidity, ash, oxidation-reduction potential (ORP), total organic carbon (TOC), dissolved oxygen, biochemical oxygen demand, chemical oxygen demand, total raw material concentration, raw material yield, ash yield, conductivity, water temperature, and pH. Among these, it is preferable that the measurement unit 30 has a measurement device for measuring the water quality of the pulp suspension by at least one selected from the group consisting of suspended solids measurement (SS), turbidity measurement, ash measurement, oxidation-reduction potential measurement (ORP), raw material total concentration measurement, raw material yield measurement, ash yield measurement, conductivity measurement, water temperature measurement, and pH measurement. These measuring devices are all well known, and commercially available devices can be used as appropriate.

[0028] Here, "suspended solids" refers to the amount of suspended solids (SS) with a diameter of 2 mm or less that are suspended in the sample (pulp suspension). Specifically, it measures the amount of material that passes through a 2 mm sieve and remains on a 1 μm filter material. "Turbidity" is a measure of the degree of cloudiness of a sample (pulp suspension). "Ash measurement" is the measurement of the amount of inorganic non-combustible matter in a sample (pulp suspension). "Oxidation-reduction potential measurement" is a value expressed as a potential difference between the oxidizing power and reducing power of a sample (pulp suspension). "Total organic carbon" is the total amount of organic matter present in a sample (pulp suspension) expressed as the amount of carbon contained in the organic matter. "Dissolved oxygen measurement" is the amount of oxygen dissolved in a sample (pulp suspension). "Biochemical oxygen demand measurement" is the amount of oxygen consumed when organic matter in a sample (pulp suspension) is decomposed by microorganisms. "Chemical oxygen demand measurement" is the amount of oxygen required to chemically oxidize the organic matter in a sample (pulp suspension). "Total raw material consistency measurement" is the consistency of all solids in the raw material (pulp suspension). The "raw material yield measurement" is the ratio of the solids concentration in the pulp suspension fed into the headbox 1 to the value obtained by subtracting the solids concentration in the white water recovered in the wire part 2 from the solids concentration. The "ash retention measurement" is the ratio of the inorganic non-combustible matter concentration in the pulp suspension fed into the headbox 1 to the inorganic non-combustible matter concentration minus the inorganic non-combustible matter concentration in the white water recovered in the wire part 2. "Conductivity measurement" refers to measuring the conductivity of a sample (pulp suspension). "Water temperature measurement" refers to measuring the water temperature of the sample (pulp suspension). "pH measurement" refers to measuring the pH of a sample (pulp suspension).

[0029] In the prediction system according to this embodiment, when it is desired to predict defects due to pitch contamination, it is preferable to perform at least one water quality measurement selected from the group consisting of suspended solids measurement, turbidity measurement, ash content measurement, raw material yield measurement, ash content retention measurement, and electrical conductivity measurement. This makes it possible to predict future defects that may occur due to pitch contamination of the paper. Furthermore, when it is desired to predict problems due to pitch contamination, it is more preferable to measure the amount of suspended solids as a water quality measurement. In this case, the prediction becomes easier and more accurate.

[0030] For example, when measuring the amount of suspended solids, the higher the value of the amount of suspended solids, the more impurities such as micropitch and inorganic dispersed matter are contained in the pulp suspension. Therefore, when the amount of suspended solids in the pulp suspension is higher than the normal value, the impurities in the pulp suspension also increase, and it is thought that the increase in impurities brought into the paper machine increases the number of micro-pitch defects, leading to pitch contamination.

[0031] When measuring turbidity, the higher the turbidity value, the more impurities such as micropitch and inorganic dispersed matter are contained in the pulp suspension. Therefore, when the amount of suspended solids in the pulp suspension is higher than the normal value, the impurities in the pulp suspension also increase, and it is thought that the increase in impurities brought into the paper machine increases the number of micro-pitch defects, leading to pitch contamination.

[0032] When measuring the ash content, the higher the ash content, the more impurities such as micro-pitch and inorganic dispersed matter are contained. Therefore, when the amount of suspended solids in the pulp suspension is higher than the normal value, the impurities in the pulp suspension also increase, and it is thought that the increase in impurities brought into the paper machine increases the number of micro-pitch defects, leading to pitch contamination.

[0033] When measuring the raw material retention, the lower the raw material retention value, the more impurities such as micropitch and inorganic dispersed matter are contained in the pulp suspension. From this, it can be considered that when the raw material yield value of the pulp suspension is lower than the normal value, the impurities in the pulp suspension also increase, and the increase in impurities brought into the paper machine increases the number of micro-pitch defects, leading to pitch contamination.

[0034] When measuring ash retention, the lower the ash retention value, the more impurities such as micropitch and inorganic dispersed matter are contained in the pulp suspension. From this, it can be considered that when the ash retention value of the pulp suspension is lower than the normal value, the impurities in the pulp suspension also increase, and therefore the number of micro-pitch defects increases as the impurities brought into the paper machine increase, leading to pitch contamination.

[0035] When measuring electrical conductivity, the higher the electrical conductivity value, the more impurities such as micropitch and inorganic dispersed matter are contained in the pulp suspension. From this, it can be considered that when the conductivity value of the pulp suspension is higher than the normal value, the impurities in the pulp suspension also increase, and therefore the number of micro-pitch defects increases as the impurities brought into the paper machine increase, leading to pitch contamination.

[0036] In the prediction system according to this embodiment, when it is desired to predict defects due to paper breakage, it is preferable to perform at least one water quality measurement selected from the group consisting of oxidation-reduction potential measurement, dissolved oxygen measurement, biochemical oxygen demand measurement, chemical oxygen demand measurement, water temperature measurement, and pH measurement, and it is more preferable to perform at least one water quality measurement selected from the group consisting of oxidation-reduction potential measurement, water temperature measurement, and pH measurement. This makes it possible to predict future problems that may occur due to paper breaks. Furthermore, when it is desired to predict defects due to paper breaks, it is more preferable to measure the oxidation-reduction potential as the water quality measurement. In this case, the prediction becomes easier and more accurate.

[0037] For example, when measuring oxidation-reduction potential, the greater the potential drop, the more likely it is that the environment is favorable for the proliferation of anaerobic bacteria such as sulfate-reducing bacteria. Slime is formed by microorganisms such as bacteria, mold, and algae. From this, it can be seen that when the oxidation-reduction potential value of the pulp suspension is lower than the normal value, a large amount of slime is generated in the pulp suspension, and as the amount of slime brought into the papermaking machine increases, the number and size of peeling defects, incorporation defects, edge split defects, etc. increase, leading to paper breaks.

[0038] When measuring water temperature, the lower the water temperature, the more optimal the temperature range for bacteria to grow, which promotes slime formation. It also promotes the aggregation and precipitation of pitch and inorganic components contained in the pulp suspension, which causes incorporation defects. From this, it is thought that when the temperature of the pulp suspension is lower than normal, a lot of slime is generated in the pulp suspension or a lot of agglomerated dirt is generated, and as a result, the amount of slime or pitch brought into the papermaking machine increases, resulting in an increase in the number of peeling defects, incorporation defects, edge split defects, tiny black spot defects, etc., leading to paper breaks and the occurrence of defects.

[0039] When measuring pH, the higher the pH, the more the aluminum ions in the aluminum sulfate in the pulp suspension become hydroxide complex ions, reducing the number of charges. This reduces the coagulation effect with the hydrated anion trash in the pulp suspension, and promotes coagulation of the pitch particles themselves. This increases the amount of fine pitch in the pulp suspension, and when it is carried into the paper machine, it increases the number of peeling defects, incorporation defects, edge split defects, and minute black spot defects, which is thought to lead to paper breaks and defects.

[0040] The measurement unit 30 periodically measures the water quality of the pulp suspension. That is, the measurement results are monitored for changes over time. The measurements may be performed every few minutes, every few hours, or once a day. The measurement unit 30 is connected to the control unit 20 via a network. Therefore, a measurement command to the measurement unit 30 is issued by the control unit 20, and the measurement results acquired by the measurement unit 30 are sent to the control unit 20. Details of this will be described later.

[0041] FIG. 2 is a schematic diagram for explaining the measurement unit in the prediction system according to this embodiment. As shown in Figure 2, the measurement unit 30 includes a branch pipe 15 attached to any pipe X through which the pulp suspension flows, a pipe Y branched by the branch pipe 15, a measuring device 11 attached to the branched pipe Y, a converter 12 capable of receiving a measurement result signal from the measuring device 11, and a gateway 13 connected to the converter 12. In the measurement section 30, the measurement device 11 measures the water quality of the pulp suspension that has flowed into the branched pipe Y.

[0042] Next, the measuring device 11 transmits a measurement result signal of the measurement result to the converter 12 . Upon receiving the measurement result signal, the converter 12 converts the measurement result signal into a numerical value and transmits it to the gateway 13 . Then, the gateway 13 transmits the numerical value (measurement result) to the control unit 20. The pulp suspension that flows into the branched pipe Y is measured by the measuring device 11 and then returned to a pipe at an arbitrary position further upstream.

[0043] 3 is a schematic diagram illustrating an example of the installation position of the measurement unit of the prediction system according to this embodiment. In FIG. 3, "P" denotes a pump, and a pulp suspension is sent in the direction of the arrow. As shown in FIG. 3, in the raw material process, the pulp is sent to a refiner 31, where the pulp is continuously subjected to processes such as defibration, beating, and purification to produce a pulp dispersion. Next, in the preparation process, water containing pulp dispersion is fed from the refiner 31 to a raw material chest 32 and a machine chest 33, to which predetermined additives are added, and a pulp suspension is prepared in a seed box 34. At this time, a portion of the pulp suspension is returned from the seed box 34 to the machine chest 33.

[0044] The pulp suspension in the seed box 34 is then sent to the head box 1 through a screen 35 that removes foreign matter. On the other hand, the white water stored in the white water pit 6 is sent to the white water silo 36 and stored there again. The white water stored in the white water silo 36 contains pulp dispersion, and a portion of it is recycled. In other words, in this case, the raw pulp suspension is prepared by mixing a portion of the white water with the pulp suspension (virgin raw material) sent from the seed box 34, and is introduced into the head box 1 through the screen 35, as described above.

[0045] In the prediction system, the measurement unit 30 has the branch pipe 15 as described above, so that it can be connected to any position as long as there is a pipe X through which the pulp suspension flows. The measuring unit 30 can be installed, for example, in a pipe on the outlet side of the raw material chest 32, a pipe used to return the pulp suspension from the seed box 34 to the machine chest 33, a pipe between the seed box 34 and the junction with the white water, a pipe on the outlet side of the white water silo 36, a pipe on the outlet side of the screen 35 (the inlet side of the bed box 1), etc. The installation position may be one or more locations. Incidentally, by installing the measuring unit 30 in the pipe between the seed box 34 and the junction with the white water, it is possible to measure the pulp suspension as virgin raw material, by installing it in the pipe on the outlet side of the white water silo 36 it is possible to measure the pulp suspension as white water, and by installing it in the pipe on the outlet side of the screen 35 it is possible to measure the pulp suspension actually charged from the head box 1. The specific installation location can be determined in light of actual measurement results and customer issues.

[0046] 1, the imaging section 40 has an imaging device for imaging the state of the paper between the dry part 4 and the reel part 5. Note that it may also have lighting and the like as necessary. Such an imaging device may be a video camera, a line sensor camera, an area sensor camera, or the like. In this way, the imaging device is installed downstream in the paper transport direction from the dry part in the papermaking process, so there is no need to enter the inside of the equipment in the wet part 2a or dry part 4 to install the imaging device, making preparation and maintenance extremely safe and easy. Furthermore, defects occurring in the stock process, preparation process and papermaking process can be reliably detected.

[0047] The imaging unit 40 continuously captures images of the paper using an imaging device to obtain image data. The resolution of the image data is preferably 10 to 500 MHz, from the viewpoint of the size of minute defects to be detected, which will be described later. The imaging unit 40 is connected to the control unit 20 via a network. Therefore, an imaging command to the imaging unit 40 is issued by the control unit 20, and image data acquired by the imaging unit 40 is transmitted to the control unit 20. This allows the control unit 20 to monitor the state of the paper over time as it goes through the processes up to the dry part 4.

[0048] FIG. 4 is a block diagram showing a control unit in the prediction system according to this embodiment. As shown in FIG. 4, the control unit 20 includes an acquisition unit 21, a detection unit 22, an extraction unit 23, a classification unit 24, a model acquisition unit 25, a setting unit 26, a transmission unit 27, and an addition command unit 28. The control unit 20 is implemented by a typical computer having a calculation unit, a storage unit, an input unit, an output unit (display unit), and the like.

[0049] As described above, the acquisition means 21 acquires image data from the imaging unit 40 and acquires measurement results from the measurement unit 30. The image data and measurement results acquired by the acquisition means 21 are then stored in a storage unit (not shown). In order to associate the image data and the measurement results with each other, it is preferable to link and acquire the data obtained at the same time as much as possible.

[0050] The detection means 22 is a means for detecting, in the captured image data, at least a precursor defect that has occurred in the paper and is a sign of a problem. As mentioned above, since the imaging device is installed downstream of the dry part 4 in the paper transport direction, the precursor defect detected in the image data will be one that occurred in the stock process, the preparation process, or a part before the dry part 4 in the papermaking process.

[0051] Examples of precursor defects include the adhesion of minute pitch (fine pitch defect), inclusion of foreign matter (inclusion defect), peeling due to the inclusion of foreign matter (peeling defect), and tearing of the paper edge (edge ​​split defect). Incidentally, an example of a defect that does not cause paper defects is the presence of insects (insect-infestation defects). In particular, minute pitch defects are precursors of pitch contamination, and incorporation defects, peeling defects, edge split defects, etc. are precursors of paper breaks.

[0052] The detection of predictive defects is carried out by digitizing the results using intensity measurement, RGB measurement, shading processing, pattern search, edge detection, etc. From the viewpoint of accuracy, the detection of predictive defects is preferably carried out by intensity measurement or RGB measurement, and more preferably by both intensity measurement and RGB measurement. For example, when the digitization is based on intensity measurement, the image is converted into a black and white binary image using a gray scale, and the shading is divided into 256 levels, for example, from 0 to 255, and digitized. Furthermore, when the digitization is based on RGB measurement, a specific color (for example, blue) may be digitized.

[0053] The extraction means 23 is a means for using the data of the precursor defect digitized by the detection means 12 to extract the feature amount of the precursor defect. In the extraction means 23, a filter method, a wrapper method, an embedding method, or the like can be appropriately adopted as a method for extracting the feature amount. Here, the extracted feature amount is preferably at least one selected from the group consisting of the quantified size of the precursor defect, the shape of the precursor defect, the shading of the precursor defect, and the position of the precursor defect. The position of the precursor defect is the position at least in the width direction of the paper where the precursor defect occurs. The extracted feature amounts are stored in the storage unit as precursor defect information.

[0054] The classification means 24 classifies the predictive defects into types based on the feature amounts of the predictive defects extracted by the extraction means 12. That is, a classification model in which reference feature amounts are set in advance is obtained, and the classification means 24 calculates the confidence level for each type of predictive defect. The higher the confidence level, the more likely it is to fall into that category. Those with low confidence are temporarily classified as "other" and then visually classified.

[0055] Here, the classification model is one in which reference features are learned by machine learning from an accumulation of actual predictive defects and their features. Furthermore, when new data on precursor defects and their feature quantities are obtained, the classification model can be further trained using the data, i.e., the reference feature quantities can be changed. This further improves the accuracy of the confidence calculated by the classification model.

[0056] In the prediction system, as described above, the control unit 20 has an acquisition means 21, a detection means 22, an extraction means 23, and a classification means 24, so that it is possible to detect precursor defects in image data and classify the precursor defects by type. In this way, even in the case of precursor defects, the tendency for the defects to increase until they occur differs depending on the type, so by deliberately classifying them, it is possible to more accurately predict the occurrence of defects in paper.

[0057] The model acquisition means 25 is a means for acquiring a prediction model that indicates the relationship between measurement information, which is data over time on the measurement results of water quality measurement, and defect number information, which is data over time on precursor defects for each type. In addition, examples of data on predictive defects over time include data on the number of predictive defects over time, data on the size of predictive defects over time, and data on the position of predictive defects (for example, the position in the width direction of the paper) over time. In other words, the prediction model is created by learning the relationship between measurement information and defect count information through machine learning. Furthermore, when new measurement information and defect count information are obtained, the prediction model can be further trained on the new information, i.e., the relationship between the two can be changed. This will improve the accuracy of paper defect prediction.

[0058] The setting means 26 is a means for setting a threshold value for the calculated measurement results obtained from the prediction model. In the setting means 26, the threshold value can be set arbitrarily. For example, the threshold value may be the value of the calculation measurement result at a stage before the number of minute pitch defects increases to the point where they become a defect. Note that the threshold value may be set in multiple stages depending on the timing and amount of chemical agent injection.

[0059] The transmitting means 27 transmits an alert when the actual measurement result exceeds a threshold value. The alert may be issued by voice or warning sound, or may be displayed on a display unit (not shown).

[0060] As described above, the prediction system has a model acquisition means 25, a setting means 26, and a transmission means 27, so that water quality measurements are taken over time, and by obtaining actual measurement results, it is possible to recognize an increase in the number of specific precursor defects. That is, an increase in the number of specific precursor defects can predict the possibility that the defect will become a paper defect in the future.

[0061] The addition command means 28 is a means for issuing a command to add or increase the amount of chemical liquid to the pulp suspension when the actual measurement result exceeds a threshold value. In the prediction system, chemicals can be added or increased to the pulp suspension by commands from the addition command means 28 . This improves the results of water quality measurements and prevents problems from occurring on the paper. The location where the chemicals are added may be selected as appropriate, for example, at the seed box 34.

[0062] The chemical preferably contains at least one selected from the group consisting of a pitch control agent, a slime control agent, a paper strength agent, a sizing agent, a retention agent, a coagulant, and aluminum sulfate. The chemical may also contain other known additives. In this case, it is possible to sufficiently prevent defects from occurring in the paper.

[0063] Here, when the prediction system predicts that the actual measurement results exceed the threshold value and that a defect due to pitch contamination will occur, it is more preferable that the chemical solution added to the pulp suspension contains at least one selected from the group consisting of a pitch control agent, a paper strength agent, a retention aid, a coagulant, and aluminum sulfate, among the above. In this case, the measurement results of the corresponding water quality measurement (for example, the amount of suspended solids) are improved, and defects caused by pitch contamination of paper can be prevented. Furthermore, in the prediction system, when the actual measurement results exceed the threshold value and a defect due to paper breakage is predicted, it is more preferable that the chemical solution added to the pulp suspension contains a slime control agent, among the above-mentioned. In this case, the measurement results of the corresponding water quality measurement (for example, oxidation-reduction potential) are improved, and problems caused by paper breaks can be prevented.

[0064] The chemical solution according to the present invention is added or increased to the pulp suspension when the actual measurement result in the above-mentioned prediction system exceeds a threshold value. The chemical solution contains at least one selected from the group consisting of a pitch control agent, a slime control agent, a paper strength agent, a sizing agent, a retention agent, a coagulant, and aluminum sulfate. The chemical solution may contain additives such as fillers, sizing agents, dispersants, emulsifiers, paper strength agents, chelating agents, pH adjusters, preservatives, viscosity adjusters, solid lubricants, wetting agents, anti-dusting agents, mold release agents, adhesives, surface modifiers, detergents, paper strength agents, retention aids, anti-slip agents, and softeners. This improves the results of water quality measurements and makes it possible to prevent problems from occurring on the paper.

[0065] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments.

[0066] In the prediction system according to this embodiment, the paper machine 10 has a wet part 2a (wire part 2 and press part 3), a dry part 4, and a reel part 5, but is not limited to these. For example, the wet part 2 a may not have the press part 3 and may be only the wire part 2 . Incidentally, the "wet part" is a part preceding the dry part, and specifically, for example, if the paper is cardboard, it refers to the wire part 2 and press part 3, and if the paper is household paper or the like that does not require the press part 3, it refers to the wire part. Note that in the above-mentioned embodiment, the wet part is explained as the wire part and press part. The paper machine 10 may further include a calender part or the like. Moreover, the paper machine 10 may be provided with a processing machine or the like that cuts and collects the paper instead of the reel part 5. Similarly, the preparation process includes, but is not limited to, a refiner 31, a raw material chest 32, a machine chest 33, a seed box 34, a screen 35, a white water silo 36, and the like.

[0067] In the prediction system according to this embodiment, white water and virgin raw material are mixed to form the raw material pulp suspension, but only virgin raw material may be used as the raw material pulp suspension, or only white water may be used as the raw material pulp suspension.

[0068] In the prediction system according to this embodiment, the measurement unit 30 includes a branch pipe 15, a measurement device 11, a converter 12, and a gateway 13, but is not limited to this configuration as long as it is capable of measurement.

[0069] In the prediction system according to this embodiment, the detection means 22 detects a predictive defect, but may also detect defects that are not predictive (hereinafter referred to as "normal defects") together with the predictive defect. In this case, the extracting means may extract the feature amounts of the predictive defects and the normal defects, and the classifying means may classify the predictive defects and the normal defects based on the feature amounts.

[0070] In the prediction system according to this embodiment, the addition command means 28 issues a command to add or increase the amount of chemical solution to the pulp suspension, but the chemical addition may be performed by a device or manually by a person.

[0071] (Correlation between suspended solids and minute pitch) FIG. 5 is a graph showing the relationship between measurement information (shown as "surface white water SS" in FIG. 5), which is data over time on the measurement results of the amount of suspended solids, and defect number information (shown as "pitch defects (all sizes)" in FIG. 5), which is data over time on the number of minute pitch defects, in the prediction system of this embodiment. The measurement results of the amount of suspended solids in Figure 5 were obtained by attaching a measuring device to the pipe on the outlet side of the white water silo 36. As shown in FIG. 5, the occurrence trend of defect number information at fine pitches shows a correlation with the measurement information. Therefore, the prediction model is created based on the relationship between measurement information, which is data over time on the measurement results of the amount of suspended solids, and defect number information, which is data over time on the number of fine pitch defects.

[0072] (Correlation between suspended solids and overall pitch) 6 is a graph showing the relationship between measurement information (shown as "surface white water SS" in FIG. 6), which is data on the measurement results of the amount of suspended solids over time, and defect number information (shown as "total defects" in FIG. 6), which is data on the total number of minute pitch defects and normal-sized pitch defects (hereinafter referred to as "normal pitch defects") over time, in the prediction system according to this embodiment. The measurement results of the amount of suspended solids in FIG. 6 were measured using a measuring device attached to the pipe on the outlet side of the white water silo 36. As shown in FIG. 6, the occurrence trend of defect count information for fine pitch and normal pitch is buried in the occurrence number of normal pitch defects other than fine pitch, and a sufficient correlation with the measurement information cannot be found. Incidentally, minute pitches grow to become normal pitch defects, and normal pitch defects correspond to the above-mentioned pitch contamination.

[0073] (Correlation between oxidation-reduction potential and paper breakage) FIG. 7 is a graph showing the relationship between measurement information, which is data over time on the measurement results of the oxidation-reduction potential, and paper break occurrence information, which is data over time on whether or not a paper break has occurred, in the prediction system according to this embodiment. The measurement results in FIG. 7 were obtained by attaching measuring devices to the pipe on the outlet side of the white silo 36 and the pipe on the outlet side of the raw material chest 32 and measuring the oxidation-reduction potential. In addition, the occurrence of paper breaks was due to the growth of peeling defects or the occurrence of precursor defects concentrating on the edge portion, and was confirmed by a paper break sensor attached to the paper machine or by visual inspection. As shown in FIG. 7, the occurrence trend of paper break occurrence information shows a correlation with the measurement information. [Industrial Applicability]

[0074] The prediction system of the present invention can be used as a system for predicting the occurrence of defects in paper when paper is produced by making a pulp suspension using a paper machine. According to the prediction system of the present invention, it is possible to predict the occurrence of defects in paper, thereby making it possible to prevent the occurrence of defects in paper. The chemical solution of the present invention makes it possible to prevent problems from occurring in paper. [Explanation of symbols]

[0075] 1. Head box 10...paper machine 11. Measuring equipment 12. Converter 13. Gateway 15 Branch pipe 2. Wire part 20 Control unit 21...Method of acquisition 22. Detection means 23...Extraction means 24...Classification means 25. Model acquisition method 26. Setting method 27. Means of communication 28... Addition command means 2a Wet part 3. Press Section 30...Measurement section 31. Refiner 32 Raw Material Chest 33 Machine Chest 34...seed box 35···screen 36. Shiramizu Silo 4. Dry part 40 Imaging unit 5. Reel Part 6. Shiramizu Pit

Claims

1. A prediction system for predicting the occurrence of defects in paper when paper is produced by making a pulp suspension using a papermaking machine having at least a wet part and a dry part, comprising: a measuring unit for measuring the water quality of the pulp suspension; an imaging unit for imaging the paper that has passed through the dry part; a control unit connected to the measurement unit and the imaging unit via a network; Equipped with the water quality measurement is at least one selected from the group consisting of suspended solids measurement, turbidity measurement, ash content measurement, oxidation-reduction potential measurement, raw material total concentration measurement, raw material yield measurement, ash content measurement, electrical conductivity measurement, water temperature measurement, and pH measurement; The control unit an acquisition unit that acquires image data from the imaging unit and acquires measurement results from the measurement unit; a detection means for detecting at least a predictive defect that is a predictor of the defect in the image data; an extraction means for extracting the feature amount of the precursor defect; a classification means for classifying the predictive defects into types based on the feature amounts; a model acquisition means for acquiring a prediction model showing the relationship between measurement information, which is data over time of the measurement results of the water quality measurement, and defect number information, which is data over time of the predictive defects for each type; a setting means for setting a threshold value for the calculated measurement result obtained from the prediction model; a transmitting means for transmitting an alert when the actual measurement result exceeds the threshold; A prediction system having:

2. The defect is a defect caused by pitch contamination, the water quality measurement is at least one selected from the group consisting of suspended solids measurement, turbidity measurement, ash content measurement, raw material yield measurement, ash content retention measurement, and electrical conductivity measurement; 2. The prediction system according to claim 1, wherein the precursor defect is a minute pitch defect caused by a minute pitch.

3. The problem is caused by a paper break, The water quality measurement is at least one selected from the group consisting of an oxidation-reduction potential measurement, a water temperature measurement, and a pH measurement; 2. The prediction system according to claim 1, wherein the precursor defect is a peeling defect caused by peeling, a gathering defect caused by gathering, or an edge split defect caused by edge split.

4. 2. The prediction system according to claim 1, wherein the control unit further comprises an addition command means for issuing a command to add or increase the amount of chemical solution to the pulp suspension when the actual measurement result exceeds the threshold value.

5. The prediction system according to claim 4, wherein the chemical solution includes at least one selected from the group consisting of a pitch control agent, a slime control agent, a paper strength agent, a sizing agent, a retention agent, a coagulant, and aluminum sulfate.

6. 3. The prediction system according to claim 2, wherein the control unit further comprises an addition command means for issuing a command to add or increase the amount of a chemical solution containing at least one selected from the group consisting of a pitch control agent, a paper strength agent, a retention aid, a coagulant, and aluminum sulfate to the pulp suspension when the actual measurement result exceeds the threshold value.

7. The prediction system described in claim 3, wherein the control unit further has an addition command means that issues a command to add or increase the amount of a chemical solution containing a slime control agent to the pulp suspension when the actual measurement result exceeds the threshold value.

8. 5. A chemical solution that is added or increased to the pulp suspension when the actual measurement result exceeds the threshold value in the prediction system according to claim 4, The chemical solution contains at least one selected from the group consisting of a pitch control agent, a slime control agent, a paper strength agent, a sizing agent, a retention agent, a coagulant, and aluminum sulfate.

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